I was waiting. But then I bought my 27" i5 and it came on Friday.
Sometimes I think you guys get too hung up on waiting (That's not a dig, just an observation) and you can end up waiting forever. I decided that in the end, the one I bought does everything I possibly need and more.
I waited and waited and waited for a Mac mini refresh that never came (this was a long while ago) and when I when I bought my 13" MBP in November everyone was saying to wait as new ones were 'definitely' coming in early Jan. Then late Jan. Then Feb. etc etc. It was April before they appeared. 6months later then when I was told to wait. I'm glad I didn't because in the end, the update to the 13" wasn't that big.
There will always be updates coming. Always. Things progress so quickly but you can wait forever before you buy. iPhones at WWDC and iPods before back to school, but other than that, I think it's pure guesswork on updates.
Just because you buy a machine today and a new one is out on Tuesday, doesn't mean you've mad a bad purchase and your iMac/MBP or whatever is no longer awesome.